"Changing the Propagation Direction of Light" Wonderful Light PPT Courseware

Description

"Changing the Propagation Direction of Light" Wonderful Light PPT Courseware

propagation of light

Objects that can emit light Light source

What path does light travel along?

The propagation path of light may be...

get conclusion:

Light travels in straight lines in a homogeneous medium

Speed: 300000 kilometers/second

It only takes 1.3 seconds for light to travel from the moon to the earth!

linear propagation of light

(1) Formation of shadow: When light encounters an opaque object during propagation, a shadow is produced behind the object.

(2) Solar eclipse

The cause of a solar eclipse: When the moon moves between the sun and the earth, and the three spheres are in a straight line, the sun's light is blocked by the opaque moon as it travels along the straight line, and the moon's shadow falls on the earth, forming a solar eclipse. Food.

(3) Lunar eclipse

The cause of a lunar eclipse: When the earth moves between the sun and the moon, and the three spheres are in a straight line, the sun's light is blocked by the opaque earth as it travels along the straight line, and the earth's shadow falls on the moon, forming a lunar eclipse. Food.

summary:

1. Objects that can emit light are called light sources;

2. Light propagates along straight lines in a uniform medium, and shadows and solar eclipses are phenomena caused by light propagating along straight lines;

practise:

1. Which of the following objects is a light source ( )

A. The moon B. Fireflies C. Stars at night

D. Polished metal that shines under the sun E. Mirror

2. When lining up, if you see a classmate in front of you blocking all the people in front of you, the line will be straightened. This can be explained by the propagation of light in a straight line.

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For more information about the "Wonderful Light Changes the Direction of Light Propagation" PPT courseware, please click the "Wonderful Light ppt Changes the Direction of Light Propagation" ppt tag.

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Update Time: 2024-11-22

This template belongs to science courseware People's Education Press Fourth Grade Science Volume 2 industry PPT template

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